Filling of features, such as vias and trenches, by copper electroplating is an essential part of the semiconductor manufacture process. It is well known, that the presence of organic substances as additives in the electroplating bath can be crucial in achieving a uniform metal deposit on a substrate surface and in avoiding defects, such as voids and seams, within the vias.
US 2004/0045832 A1 discloses methanesulfonate based compositions for copper electroplating of vias and trenches having diameters of 1 to 500 micrometers and high aspect ratios like vias or microvias. The additives used are high molecular weight polyether-type suppressors, sulfur-atoms containing accelerators (brighteners) like bissulfopropyl disulfide (SPS, 3,3′-dithiobis(1-propanesulfonic acid)), and levelers like alkylated polyalkyleneimines or hydroxyethyl imidazolidinethione.
US 2009/0035940 A1 discloses the use of polarizeres and depolarizers as additives for rapid and defect-free copper electroplating of large-size TSV features. A typical and preferred depolarizer is SPS. A typical and preferred polarizer is methyl quaternized polyvinylpyridine.
U.S. Pat. No. 6,425,996 B1 discloses leveling agents comprising the reaction product of polyaminoamides and epihalohydrins, dihalohydrins and 1-halogen-2,3-propanediols, respectively. Phthalic or terephatlic acid are mentioned as potential educts to prepare the polyaminoamide intermediates.
EP 1978134 A1 discloses leveling agents comprising polyethoxylated polyamides or polyethoxylated polyaminoamides.
US 2011/062029 discloses a copper electroplating polyaminoamide additive being prepared by modifying a polycondensation product composed of diethylene triamine, adipic acid and ε-caprolactam with epichlorhydrin.
WO 2011/064154 discloses the use of polyaminoamides in copper electoplating baths.
Feature dimensions in 3DTSV applications are relatively large (micrometer size) and therefore feature geometry does not have as much impact on the copper grain size at plating as it has in advanced dual damascene application (nanometer size). In large features copper grain size as plated is mainly influenced by the plating chemistry that was used for the copper deposition. When applying a plating chemistry that results in small copper grains a strong recrystallization process to form large copper grains might occur in the following anneal process. Strong recrystallization during annealing induces stress on the substrate which can cause damage. Stress evolution can be minimized or avoided when large copper grains already form in the features during the copper deposition.
It is an object of the present invention to provide a copper electroplating bath providing rapid deposition of copper into micrometer or nanometer scale features without forming defects, such as but not limited to voids.
It is a further object of the present invention to provide copper deposits into micrometer scale features having an increased grain size and thus leading to reduced stress during annealing.
Without the intention to be bound to any particular theory it is believed that the grains size is strongly related to the amount of impurities in the deposited copper layer. It is therefore a further object of the present invention to provide copper deposits into micrometer scale features having reduced impurity content.
It is a further aspect of the present invention to provide a copper electroplating additive having good superfilling properties, in particular suppressing agents capable of providing a substantially voidless and seamless filling of features on the nanometer and on the micrometer scale with a metal electroplating bath, preferably a copper electroplating bath. It is a further object of the present invention to provide a copper electroplating additive capable of providing a substantially voidless and seamless filling of features having a convex shape.